fix 'maximum recursion depth is exceeded' for sqlalchemy objects

Author: Victor Naumov

devtools/prettier.py

@@ -15,6 +15,8 @@
 
 try:
     from sqlalchemy import inspect as sa_inspect
+    from sqlalchemy.orm import Mapper as sa_Mapper
+    from sqlalchemy.sql.schema import Table as sa_Table
 except ImportError:
     sa_inspect = None  # type: ignore[assignment]
 
@@ -86,6 +88,7 @@ def __init__(
             (DataClassType, self._format_dataclass),
             (SQLAlchemyClassType, self._format_sqlalchemy_class),
         ]
+        self.visited: 'Set[int]' = set()
 
     def __call__(self, value: 'Any', *, indent: int = 0, indent_first: bool = False, highlight: bool = False) -> str:
         self._stream = io.StringIO()
@@ -261,7 +264,44 @@ def _format_dataclass(self, value: 'Any', _: str, indent_current: int, indent_ne
             field_items = ((f, getattr(value, f)) for f in value.__slots__)
         self._format_fields(value, field_items, indent_current, indent_new)
 
+    def _format_sqlalchemy_visited(self, value: 'Any') -> None:
+        if sa_inspect is None:
+            self._stream.write(f'"<visited {value!r})>"')
+            return
+
+        inst_state = sa_inspect(value, raiseerr=False)
+        if inst_state is None or not isinstance(inst_state.mapper, sa_Mapper):
+            self._stream.write(f'"<visited {value!r})>"')
+            return
+
+        mapper = inst_state.mapper
+        if isinstance(mapper.persist_selectable, sa_Table):
+            tablename = mapper.persist_selectable.name
+        else:
+            tablename = mapper.class_.__name__
+
+        unloaded_orm_fields = inst_state.unloaded
+        fields_list = []
+        for c in mapper.columns:
+            if not c.primary_key or c.name in unloaded_orm_fields:
+                continue
+
+            try:
+                _value = getattr(value, c.name)
+                fields_list.append(f'{c.name}={_value}')
+            except AttributeError:
+                pass
+
+        fields = ', '.join(fields_list)
+        self._stream.write(f'"<visited {tablename}({fields})>"')
+
     def _format_sqlalchemy_class(self, value: 'Any', _: str, indent_current: int, indent_new: int) -> None:
+        if id(value) in self.visited:
+            self._format_sqlalchemy_visited(value)
+            return
+
+        self.visited.add(id(value))
+
         if sa_inspect is not None:
             state = sa_inspect(value)
             deferred = state.unloaded
@@ -271,7 +311,7 @@ def _format_sqlalchemy_class(self, value: 'Any', _: str, indent_current: int, in
         fields = [
             (field, getattr(value, field) if field not in deferred else '<deferred>')
             for field in dir(value)
-            if not (field.startswith('_') or field in ['metadata', 'registry'])
+            if not (field.startswith('_') or field in ['metadata', 'registry', 'awaitable_attrs'])
         ]
         self._format_fields(value, fields, indent_current, indent_new)